382 METALLURGY OP IRON AND STEEL. rise of 0.01 per cent, of carbon is only 4 pounds. In the acid steel the base is 0.4 per cent, of manganese; in the basic steel it is 0.3 per cent. The results are tabulated in Table XVII-V. FIG. XVII-E. EFFECT • OF MANGANESE ON BASIC STEEL. 47,001. 4400. ~*&L & --3O .70 As in the case of acid steel before explained, an attempt was made to get a uniform value for manganese. The figure found for basic steel was 160 pounds for each .01 per cent, over .30 per cent., but as with acid steel it was found that such a formula did not give as close agreement between the calculated and the actual ultimate strength as when the variable value of manganese was used.